This invention relates in general to the treatment of a production interval of a wellbore to stimulate hydrocarbon production and prevent the production of fine particulate materials and, in particular, to an apparatus and method for progressively gravel packing or progressively frac packing the production interval of the wellbore.
It is well known in the subterranean well drilling and completion art that relatively fine particulate materials may be produced during the production of hydrocarbons from a well that traverses an unconsolidated or loosely consolidated formation. Numerous problems may occur as a result of the production of such particulate. For example, the particulate cause abrasive wear to components within the well, such as tubing, pumps and valves. In addition, the particulate may partially or fully clog the well creating the need for an expensive workover. Also, if the particulate matter is produced to the surface, it must be removed from the hydrocarbon fluids using surface processing equipment.
One method for preventing the production of such particulate material is to gravel pack the well adjacent the unconsolidated or loosely consolidated production interval. In a typical gravel pack completion, a sand control screen is lowered into the wellbore on a work string to a position proximate the desired production interval. A fluid slurry including a liquid carrier and a relatively coarse particulate material, such as sand, gravel or proppants which are typically sized and graded and which are typically referred to herein as gravel, is then pumped down the work string and into the well annulus formed between the sand control screen and the perforated well casing or open hole production zone.
The liquid carrier either flows into the formation or returns to the surface by flowing through a wash pipe or both. In either case, the gravel is deposited around the sand control screen to form the gravel pack, which is highly permeable to the flow of hydrocarbon fluids but blocks the flow of the fine particulate materials carried in the hydrocarbon fluids. As such, gravel packs can successfully prevent the problems associated with the production of these particulate materials from the formation.
It is sometimes desirable to perform a formation fracturing and propping operation prior to or simultaneously with the gravel packing operation. Hydraulic fracturing of a hydrocarbon formation is sometimes necessary to increase the permeability of the production interval adjacent the wellbore. According to conventional practice, a fracture fluid such as water, oil, oil/water emulsion, gelled water or gelled oil is pumped down the work string with sufficient volume and pressure to open multiple fractures in the production interval. The fracture fluid may carry a suitable propping agent, such as sand, gravel or proppants, which are typically referred to herein as proppants, into the fractures for the purpose of holding the fractures open following the fracturing operation.
The fracture fluid must be forced into the formation at a flow rate great enough to fracture the formation allowing the entrained proppant to enter the fractures and prop the formation structures apart, producing channels which will create highly conductive paths reaching out into the production interval, and thereby increasing the reservoir permeability in the fracture region. As such, the success of the fracture operation is dependent upon the ability to inject large volumes of hydraulic fracture fluid along the entire length of the formation at a high pressure and at a high flow rate.
It has been found that it is difficult to achieve a complete gravel pack of the desired production interval either independent of or as part of a fracturing operation, particularly in long or inclined/horizontal production intervals. These incomplete packs are commonly a result of the liquid carrier entering the permeable portions of the production interval causing the gravel to form a sand bridge in the annulus. Thereafter, the sand bridge prevents the gravel pack slurry from flowing to the remainder of the annulus which, in turn, prevents the placement of sufficient gravel in the remainder of the annulus.
Therefore a need has arisen for an apparatus and method that are capable of creating fractures along the entire length of a production interval. A need has also arisen for such an apparatus and method that can produce a complete gravel pack of the wellbore adjacent to the production interval either independent of or as part of the fracturing of the production interval. Further, a need has arisen for an apparatus and method that are capable of stimulating the production interval to enhance production and gravel packing the production interval to prevent the production of fine particulate materials when production commences.
The present invention disclosed herein comprises an apparatus and method that is capable of enhancing production from a production interval by creating fractures throughout the entire interval and producing a substantially complete gravel pack of the wellbore adjacent to the production interval to prevent the production of fine particulate materials when production commences. The apparatus and method of the present invention achieves these results by progressively treating the production interval from one end to the other.
The apparatus comprises a sand control screen that is positioned within the wellbore and a fluid delivery tubular positioned adjacent to sand control screen in the wellbore. The fluid delivery tubular progressively allows fluid communication from the interior of the fluid delivery tubular to the exterior of fluid delivery tubular from a first end to a second end of the interval, thereby delivering the treatment fluid along the entire length of the interval.
The fluid delivery tubular may comprises a plurality of actuatable members. The actuatable devices may be rupture disks, pressure actuated one-way valves or other pressure actuated devices that are positioned along a portion of the length of the fluid delivery tubular such that the pressure required to actuate the actuatable members progressively increases from the first end to the second end of the interval. Alternatively, the actuatable device may be progressively actuated from the first end to the second end of the interval using signals sent from the surface using hard wire connections, fiber optics, hydraulics or wireless telemetry.
The fluid delivery tubular may alternatively comprise a perforated pipe having a plurality of removable members positioned on the interior or the exterior thereof. The removable members may be propellants or other combustible material members each having an initiator. The initiators may be activated using signals. Alternatively, the initiators may have pressure activated firing devices that are positioned such that the pressure required to fire the pressure activated firing devices progressively increasing from the first end to the second end of the interval.
The removable members may alternatively be friable members that are progressively removable from the first end to the second end of the interval. Each friable member may include a pressure actuated vibration generator. In this case, the pressure actuated vibration generators are positioned such that the pressure required to activate the pressure actuated vibration generators progressively increasing from the first end to the second end of the interval. Alternatively, each of the friable members may have a vibration generator that activated by a signal sent from the surface.
The method of the present invention comprises traversing the formation with the wellbore, locating a sand control screen eccentrically within the wellbore proximate the formation, positioning a fluid delivery tubular adjacent to the sand control screen within the wellbore, injecting a treatment fluid into the fluid delivery tubular, progressively establishing fluid communication between the interior of the fluid delivery tubular and the exterior of the fluid delivery tubular from the first end to the second end of the interval and terminating the injecting when the interval is treated.